It is well known that a general communication system comprises a plurality of NEs (Network Elements), where each of the NEs measures performance information and notifies it to an NMS (Network Management System). The performance information may be the number of pieces of data sent to or received from opposing NEs. The NMS displays performance information notified from each of the NEs on a screen provided in the NMS itself. By checking the performance information displayed on the NMS screen, an administrator of the communication system grasps the operation state of the general communication system.
Incidentally, a system comprising redundantly configured devices (hereafter, referred to as a “redundant system”) is known. A redundant system is disclosed in Patent Literature 1 (PTL 1) described below.
The redundant system of PTL 1 comprises two devices which have the same function to process an inputted signal. Each of the devices notifies its internal status to the other and, on the basis of the own internal status and an internal status notified from the other device, automatically determines whether itself currently is to be the active device or the standby device, thereby constituting the redundant configuration. One of the devices having determined itself to be the active device processes an inputted signal.
As the configuration and operation described above, in the redundant system of PTL 1, two devices automatically constitute a redundant configuration and one of them having determined itself to be the active device processes an inputted signal.